This invention relates to a chain saw guide bar provided with a detachable nose part.
In U.S. Pat. No. 3,762,047 a saw guide bar with detachable nose part is disclosed which represents a type being presently marketed. The patent discloses a nose part which is fastened to a main part of the saw guide bar by means of rivets. In this connection, the nose part is provided with a central, projecting part which fits into a corresponding recess in the main part of the saw guide bar. This recess causes a drastic weakening of the main part of the saw guide bar and may lead to fracture, whereby the whole saw guide bar has to be replaced. Further, the known saw guide bar is provided with joints formed by the opposing edges of the nose part and main part. This arrangement causes at least three drawbacks. Firstly, it is difficult to get enough stiffness in the joint. Secondly, the wear of the chain will be great when the chain hits against the joints positioned side-by-side between the two side plates. Thirdly, the wear of the edge of the saw guide bar will also be great, due to the hits of the saw chain against the edge.
This invention is intended to remove the mentioned drawbacks which are connected with known types of saw guide bars provided with a detachable nose part.
In accordance with the invention, the joints between the nose part and main part are displaced from one another in the direction of chain travel as regards both the horizontal and vertical center planes.